JPH08149258A - Image input device - Google Patents

Abstract

(57) [Abstract] [Purpose] Even if the length of the light source is not enough for the width of the document, the document can be illuminated uniformly. A reflector 11 having a V-shaped cross section is provided at the center of an opening 2a of an illumination holder 2 that houses and holds a fluorescent tube, and the oblique reflecting surface of the reflector 11 allows light emitted from the fluorescent tube to the left and right sides. The original 4 is evenly illuminated by dividing and reflecting it.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an image input device for reading an image of an original by using a solid-state image pickup device (hereinafter referred to as CCD) as photoelectric conversion means, and more particularly, an image capable of uniformly illuminating the original. Regarding the input device.

[0002]

2. Description of the Related Art As an apparatus for reading an image of a document, the document is irradiated with light emitted from a light source as a light emitting means, and reflected light or transmitted light from the document is guided onto a CCD and is composed of a plurality of lenses. Generally, the image is focused on the CCD by the imaging lens unit and the image data of the original is read.

When reading an image of a color original, the reflected light or transmitted light from the original is separated into three colors of red (R), green (G) and blue (B), and the respective lights are CC.
The detection is performed by the pixels arranged in D at a predetermined pitch.

A schematic structure of an example of a conventional image input device as described above is shown in FIGS. 3 and 4, both ends of a fluorescent tube 1 which is a straight tube-shaped light source are held by a lighting holder 2 as a box-shaped holding means having an opening 2a formed in the front surface. Reflecting plates 3a, 3b, and 3c are provided on the inner surface on the side opposite to the opening 2a of the illumination holder 2 and on the upper, lower, left, and right inner surfaces, respectively.

The reflection original 4 is placed on a mounting table (not shown), and the illumination holders 2 are arranged on both sides of the two opposite sides of the reflection original 4 with the openings 2a opposed to each other. An imaging lens unit 5 is provided above the center of the reflection original 4 with the optical axis perpendicular to the reflection original 4, and C is provided on the opposite side of the reflection original 4 with the imaging lens unit 5 interposed therebetween.
CD6 is arranged.

In the image input device constructed as described above, the light emitted from the fluorescent tube 1 is reflected directly or by the reflection plates 3a, 3b and 3c to illuminate the reflection original 4. The image of the reflection original 4 illuminated by the fluorescent tube 1 and the reflection plate 3 is focused on the CCD 6 by the imaging lens unit 5 and converted into image data.

[0007]

However, the straight tube type fluorescent tube 1 used for the above-mentioned illumination mechanism generally has a large amount of light in the central portion but a small amount of light at both ends. If the length of the fluorescent tube 1 is sufficiently longer than the width of the original 4, the amount of light on the original 4 is substantially uniform, but the length of the fluorescent tube 1 is not sufficiently longer than the width of the original 4. However, although some correction is possible depending on the shape of the reflection plate 3, the light amount at the central portion of the document 4 is large and the light amount at both end portions is small.
As a result, there is a problem in that uniform illumination cannot be obtained, image data becomes uneven, and in the case where this image is viewed on a CRT or the like, a faithful image cannot be reproduced.

The present invention has been made in view of the above circumstances, and provides an image input device capable of uniformly illuminating an original even when the length of the light source is not sufficient for the width of the original. With the goal.

[0009]

In order to achieve the above object, the present invention according to claim 1 provides a straight-tube light emitting means (for example, the fluorescent tube 1 in FIG. 2) and a light emitted from the fluorescent tube 1. A reflection unit (for example, the reflection plate 3 in FIG. 1) that reflects the light toward the document (for example, the document 4 in FIG. 1) and a photoelectric conversion unit (for example, in FIG. 1) that converts the reflected light or the transmitted light from the document 4 into an electric signal. In an image input device provided with a CCD 6) and an image forming means for forming an image of the original 4 on the CCD 6 (for example, the image forming lens section 5 in FIG. 1), the fluorescent tube 1 is housed and held, and an opening portion (front side) is provided. For example, the holding means (for example, the illumination holder 2 in FIG. 1) having the opening 2a) shown in FIG. 1 is provided in parallel to the fluorescent tube 1 and on the inner surface of the illumination holder 2 on the side opposite to the opening 2a. The first reflection means (for example, the reflection plate 3 in FIG. 2)
a, 3b, 3c) and a second reflecting means provided in the center of the opening 2a and having a reflecting surface for splitting and reflecting the light emitted from the fluorescent tube 1 into the left and right sides (for example, the reflector 11 in FIG. 1).
And characterized in that:

The image input device according to the second aspect is characterized in that the illumination holder 2 is arranged in parallel in proximity to at least one of two opposite sides of the original 4.

[0011]

In the image input device having the above structure, the fluorescent tube 1
The light emitted from is divided into left and right sides by the reflector 11 provided at the center of the opening 2a of the illumination holder 2 and emitted from both sides of the reflector 11 of the opening 2a. On the other hand, even if the fluorescent tube 1 is not long enough, the light amount distribution on the original 4 can be made substantially uniform.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the image input device of the present invention will be described below with reference to the drawings.

1 and 2 show the configuration of an embodiment of the present invention. 1 and 2, parts corresponding to those of the conventional example shown in FIGS. 3 and 4 are designated by the same reference numerals,
The description will be omitted as appropriate. The feature of this embodiment is that the reflector 11 is provided at the center of the opening 2a of the illumination holder 2.
The reflector 11 has a V-shaped cross section that widens toward the opening, and each has a reflecting surface 11a.

According to the above structure, of the light emitted from the fluorescent tube 1, the light at the central portion is the both reflecting surfaces 11a of the reflector 11.
Is divided into left and right by and reflected by the reflector 3
The light reflected by a, 3b, and 3c becomes light that illuminates both ends of the original 4. As a result, the light quantity at both ends of the original 4 increases, and the light quantity distribution on the original 4 apparently becomes uniform because the light quantity at the central portion decreases.

In the above embodiment, the case where the cross-sectional shape of the reflector 11 is V-shaped has been described, but the cross-sectional shape is not limited to this, and the light emitted from the fluorescent tube 1 is divided into right and left and reflected. If it is, the cross-sectional shape may be U-shaped, semicircular, or the like. When the original 4 has a small area, the illumination holder 2 may be arranged on only one side of the original 4. Further, the same effect can be obtained when the original 4 is not a reflective original but a transparent original. In this case, the illumination holder 2 is arranged on the opposite side of the CCD 6 with respect to the original 4.

[0016]

As described above, according to the image input device of the present invention, the light emitted from the light emitting means is split into the left and right sides and reflected at the center of the opening of the holding means for holding the light emitting means. Since the means is provided, the quantity of light in the central portion of the light emitting means, which apparently has a large quantity of light, decreases, and the quantity of light in the end portions where the quantity of light is small increases. As a result, the amount of light on the original can be made substantially uniform.

[Brief description of drawings]

FIG. 1 is an exploded perspective view showing a basic configuration of an embodiment of an image input apparatus of the present invention.

2 is a cross-sectional view of FIG.

FIG. 3 is an exploded perspective view showing a basic configuration of an example of a conventional image input device.

FIG. 4 is a cross-sectional view of FIG.

[Explanation of symbols]

 1 Fluorescent Tube (Light Emitting Means) 2 Illumination Holder 2a Opening 3 Reflector (First Reflecting Means) 4 Original 5 Imaging Lens (Imaging Means) 6 CCD (Photoelectric Converting Means) 11 Reflector (Second Reflection) means)

Claims (2)

[Claims] 1. A straight tubular light emitting means, a reflecting means for reflecting light emitted from the light emitting means toward a document, a photoelectric conversion means for converting reflected light or transmitted light from the document into an electric signal, An image input device comprising: an image forming unit for forming an image of a document on the photoelectric conversion unit; a holding unit for accommodating and holding the light emitting unit and having an opening formed in a front surface; First reflecting means provided in parallel to the inner surface of the holding means on the side opposite to the opening, and light emitted from the light emitting means, which is provided at the center of the opening, is divided into left and right sides and reflected. An image input device, comprising: 2. The holding means is arranged so as to face the original 2
The image input device according to claim 1, wherein the image input device is arranged in parallel with at least one of the sides.